In a prospective design the investigators are studying the longitudinal patterns of behavior of 248 male chronic opioid users in San Antonio. The subjects were hospitalized for treatment of opioid dependence during the years 1964 through 1967. Data are collected by periodic interviews with subjects and by review of records about subjects in law enforcement, correctional, and treatment agencies. In addition data are collected about brothers who did not use opoid drugs daily, and about community conditions affecting opioid use. Subjects are predominantly Mexican-American. They began opioid use at the median age of 17; in 1978 the group would have a median age of 40 if all were living. The death rate is high, about 3 times the death rate of comparably aged males in San Antonio. The study is producing statistical descriptions of the chronological experiences of the subjects, of the relation of background predictors to long-term outcomes, and of the consequences of treatment and correctional interactions.